<html>
<head>
	<meta charset="UTF-8">
	<meta content="IE=edge" http-equiv="X-UA-Compatible">
	<meta content="initial-scale=1.0, maximum-scale=1.0, user-scalable=no, width=device-width" name="viewport">
	<title>3006：基站建设</title>
	<!-- css -->
	<link href="../css/base.min.css" rel="stylesheet">
	<link href="../css/project.min.css" rel="stylesheet">
	
	<!-- favicon -->
	<!-- ... -->
</head>
<body class="page-brand">
	<header class="header header-transparent header-waterfall ui-header">
		<ul class="nav nav-list pull-left">
			<li>
				<a data-toggle="menu" href="#menu">
					<span class="icon icon-lg">menu</span>
				</a>
			</li>
		</ul>
		<a class="header-logo header-affix-hide margin-left-no margin-right-no" data-offset-top="213" data-spy="affix">基站建设</a>
		<span class="header-logo header-affix margin-left-no margin-right-no" data-offset-top="213" data-spy="affix">基站建设</span>
	</header>
	<nav aria-hidden="true" class="menu" id="menu" tabindex="-1">
		<div class="menu-scroll">
			<div class="menu-content">
				<a class="menu-logo" href="../index.html">BZOJ离线题库</a>
				<ul class="nav">
					<li>
						<a class="waves-attach" data-toggle="collapse" href="#problems">题目</a>
						<ul class="menu-collapse collapse in" id="problems">
							<li>
								<a class="waves-attach" href="../index.html">主页</a>
							</li>
							<li>
								<a class="waves-attach" href="../list.html">题目列表</a>
							</li>
						</ul>
					</li>
					<li>
						<a class="collapsed waves-attach" data-toggle="collapse" href="#about">关于</a>
						<ul class="menu-collapse collapse" id="about">
							<li>
								<a class="waves-attach" href="../about.html">关于此项目</a>
							</li>
						</ul>
					</li>
					
				</ul>
			</div>
		</div>
	</nav>
	<main class="content">
		<div class="content-header ui-content-header">
			<div class="container">
				<h1 class="content-heading">
                基站建设                </h1>
                <p>时间限制：200s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：512MB</p>			</div>
		</div>
		<div class="container">
			<section class="content-inner margin-top-no">
				<div class="row">
					<div class="col-lg-13 col-md-13">
						<div class="card margin-bottom-no">
							<div class="card-main">
								<div class="card-inner">
									
                                <h3>题目描述</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Up主家终于买电脑了，但是接下来有各种问题要处理。首要解决的问题就是网络问题。他要从移动公司开始，通过一些基站来传递网络到他家。</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 为了简化问题，我们假设移动公司，所有的基站，up主家位于同一条直线上，他们都位于这一条直线上的某一点x，这些点不会重合。每个基站发射和接收的范围都是一个切于地面的圆，发射的半径r1是固定的，接收半径r2是可调的的。如下图：</span></div>
<div><span style="font-size: medium"><img height="270" alt="" width="537" src="../file/3006_0.jpg" /></span></div>
<div></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 一个点i如果能从另一个点j接收到信号(当且仅当x[j] &lt; x[i])，必须满足i的接收范围与j的发射范围相切，并且需要付sqrt(r2[i])的额外费用。同时启动每一个点i都需要费用v[i].</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 当然一个点如果能够发射的up主家只需要这个点的发射范围与up主家所在的竖线相切或相交即可，如下图：</span></div>
<div><span style="font-size: medium"><img height="262" alt="" width="373" src="../file/3006_1.jpg" /></span></div>
<div></div>
<div><span style="font-size: medium">当然费用越少就越好咯，于是up主想要请你帮他的忙。</span></div></p><hr/><h3>输入格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 第一行两个整数n,m.表示基站个数(包括移动公司)，up主家的坐标。(保证大等于所以基站的坐标)</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 记下来n行，每行三个整数x[i],r1[i],v[i],表示每个基站的坐标，发射范围以及费用。</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; X[i]是按照坐标从小到大输入的，移动公司位于最小的那个坐标。</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; R为1..n的排列。</span></div></p><hr/><h3>输出格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 一个实数，保留小数点后三位。</span></div>
<div><span style="font-size: medium"><b>&nbsp;</b></span></div></p><hr/><h3>样例输入</h3><pre>10 33
5 4 660
10 2 2040
11 6 3207
14 5 2006
18 3 6130
19 9 3363
22 1 1265
25 8 2836
27 10 7961
29 7 9075
 
</pre><hr/><h3>样例输出</h3><pre>3501.000
 
 
 </pre><hr/><h3>提示</h3><p><p>对于100%的数据 n&lt;=5*1000000,x[i],m &lt;= 10^12,v[i] &lt;= 10000<br />
</p></p><hr/><h3>题目来源</h3><p>没有写明来源</p>
								</div>
							</div>
						</div>
					</div>
				</div>
				
				
			</section>
		</div>
	</main>

	<div class="fbtn-container">
		<div class="fbtn-inner">
			<a class="fbtn fbtn-lg fbtn-brand-accent waves-attach waves-circle waves-light waves-effect" data-toggle="dropdown" aria-expanded="true"><span class="fbtn-text fbtn-text-left">Menu</span><span class="fbtn-ori icon">apps</span><span class="fbtn-sub icon">close</span></a>
			<div class="fbtn-dropup">
				<a class="fbtn fbtn-brand waves-attach waves-circle waves-light waves-effect" href="../list.html" target="_self"><span class="fbtn-text fbtn-text-left">题目列表</span><span class="icon">menu</span></a>
				<a class="fbtn fbtn-green waves-attach waves-circle waves-effect" href="../index.html" target="_self"><span class="fbtn-text fbtn-text-left">返回主页</span><span class="icon">home</span></a>
				<a class="fbtn waves-attach waves-circle waves-effect" href="http://www.lydsy.com/JudgeOnline/submitpage.php?id=3006" target="_blank"><span class="fbtn-text fbtn-text-left">提交代码</span><span class="icon">send</span></a>
				<a class="fbtn fbtn-orange waves-attach waves-circle waves-effect" href="http://www.lydsy.com/JudgeOnline/wttl/wttl.php?pid=3006" target="_blank"><span class="fbtn-text fbtn-text-left">试题讨论</span><span class="icon">chat</span></a>
				
			</div>
		</div>
	</div>

	<!-- js -->
	<script src="../js/jquery.min.js"></script>
	<script src="../js/base.min.js"></script>
	<script src="../js/project.min.js"></script>
</body>
</html>